perf(git): always flush after every line
perf(git): always flush after every line

This addresses the problem described in the parent commit. Note that
despite what the comment here says, flushing on every line is plenty
fast (tested with `git log -p`; it's fine...).

So "perf" here means perceived perf (responsiveness).

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent